Projectile



(No Model.)

J. G. BUTLER.

PROJEGTILE.

No. 290,970. Patented Dec. 25, 1883.

WITNESSES.

INVENTUH.

sra'rns PROJECTILE.

SPECIFICATION forming part of Letters Patent N0. 290,970, dated December 25, 1883,

Application filed February 12, 1883.

To aZZ whom, it may concern/.-

Be it known that 1, JOHN G. BUTLER, of Vatertown, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Projectiles for Breech-Loading Rified Guns, of which the following is a full and exact description, reference being had to the accompanying drawings, forming part of this specification.

My invention is confined to the device usually attached to an elongated projectilefor the purpose of imparting to it the rotation due to the twist of the riding.

Projectiles for breech-loading rifles usually consist of an iron or steel body circumscribed by one or two narrow bands of softer metal, which project above the cylindrical surface of the shot and exceed in diameter the rifled portion of the bore of the gun. \Vhe'n inserted in the chamber of the gun, the projecting band lodges against the rilling, and is afterward forced through the bore by the action of the discharge, and the band being cut into by the ritling the projectile is forced to follow the twist. These bands,though frequently grooved externally to diminish friction, are nevertheless solid and fill the space between the surface of the bore on the one hand and the hard, unyielding body of the shot on the other. They can yield only by the compression and flow of the metal itself, and the consequent forcing of the projectile is sometimes objectionably Violent. Moreover. the attrition of the bore as the projectile passes through wears off some of the original impression of the ritling, and thus the band or rotating device which may have been too tight at the start of the projectile may become too loose for the best results by the time it reaches the muzzle.

It is the object of my invention to avoid both of these evils, and this Ido by construct ing and applying a band, which, while yielding more readily than the solid band to the forcing action of the charge, shall at the same time possess sufficient elasticity to maintain a close lit throughout the entire passage of the projectile in the bore.

Referring to the accompanying drawings, Figure I illustrates my invention as applied to a shell for a rifled gun, and in this drawing the form of the band is distinctly shown.

(No model.)

This band S is observed to be corrugated, and is shown on a larger scale in Fig. III, which gives part of the band and projectile in section. Furnished with such a band, the projectile, when driven through the rifling, meets with sufficient resistance to impress the rifiing upon the band,which, however, is more yielding than solid metal would be, and opposes less resistance than the solid band during the initial progress of the projectile. The impressions of the rilling are taken upon the ridges b b, and the form of the band gives to it a limited but sufficient amount of elasticity caused by the corrugated or waved form of the band. Again, as each of these ridges has under it an air-space, a, the effect is not only to render compression somewhat easier, but to aid the elastic resistance of the band and keep it always distended sufficiently to insure a close fit or good mechanical bearing through out the bore. The compression of the band tightens an already good fit in the under-cut of the projectile in which it is secured, and the escape of the confined airis not sufiiciently rapid to affect any elastic effort it is capable of, and this action of the band is confined within narrow limits. In other words, it wants only sufficient elasticity to keep distended in the here.

The annular under-cut channel may be cast or cut in the body of the projectile, and when the material is such as to render this diflicultt-he corrugated band S may be applied to a band of softer material-likc wrought-iron, castiron, or mild stcel-which has previously been attached to the base of the projectile proper by casting or upsetting it upon the same. This latter plan is illustrated in Fig. II, where 1? represents the hard projectile, B, the softer part, and S the corrugated band in position.

The resistance which this projectile offers to forcing may be regulated by increasing the thickness orhardening the material of the corrugated band. Its elasticity may also be increased, while smaller grooves will increase the stiffness and diminish the elasticity ofthe band.

I am aware that proj ectiles have before been provided with corrugated bands, some supported upon flanges of th e projectile, and others provided with openings, through which gas might enter the spaces beneath the corrugations or air might escape therefrom, andI do not claim metal bands adapted to fit said grooves, the such as in ;y invention. ridges of said corrugations forming air-spaces Haviv 4?; thus described my invention,whatI between the bands and the body of the proclaim and desire to secure by Letters Patent, jectile, as and for the purpose specified.

I JOHN G. BUTLER. A rifle-projectile having one or more cir- I WVitnesses: cumferential grooves, in combination with one I CHAS. A. GREGG, or more oircumferentially-corrugated sheet- GEO. MILLS. 

